In a class 20% of students wore glasses, 30% wore contact lenses, and 10% wore both glasses and contact lenses. What percentage of students in the class wear elder glasses or contact lenses?
In a class 20% of students wore glasses, 30% wore contact lenses, and 10% wore both glasses and contact lenses. What percentage of students in the class wear elder glasses or contact lenses?
Explanation
Given:
- Percentage of students who wore glasses: 20%
- Percentage of students who wore contact lenses: 30%
- Percentage of students who wore both glasses and contact lenses: 10%
Let's denote:
-A : Set of students who wore glasses
-B : Set of students who wore contact lenses
The formula for the union of two sets is given by:
Substitute the given values:
P(students who wear glasses or contact lenses) = 20% + 30% - 10% = 40%